Jacques Charles, in 1787, formulated the relationship between the volume and temperature of a given mass of a dry gas at constant pressure called Charles' Law which states that "At constant pressure, the volume of a fixed mass of dry gas is directly proportional to the absolute temperature;

It can be mathematically expressed as

The magnitude of constant depends on pressure, mass and nature of a gas.

Charles' law is useful for calculating the volume of a gas at any required temperature if the volume at some other temperature is known by using the following equation.